while (in another case) a
DNA copy of the K1 dsRNA was introduced in a
K2 strain of S. cerevisiae [12]. However, even a K1/
K2 double killer S. cerevisiae is very limited as to
the variety of yeast contaminants that can be
eliminated. Rather, attention is now focused on
the identi®cation of genes encoding more effective
zymocins in other yeasts such as Pichia and
Hanseniaspora and their possible introduction into
S. cerevisiae.